Definition of Unconsciousness, temporary

Unconsciousness, temporary: A partial or complete loss of
consciousness with interruption of awareness of oneself and ones
surroundings. When the loss of consciousness is
temporary and there is spontaneous recovery, it is referred to as
syncope or, in nonmedical quarters, fainting. Syncope accounts for nearly
one in every 30 visits to an emergency room.

Syncope is due to a temporary reduction in blood flow and
therefore a shortage of oxygen to the brain. This leads to
lightheadedness or a "black out" episode, a loss of consciousness.
Temporary impairment of the blood supply to the brain can be caused
by heart conditions and by conditions that do not directly involve
the heart:

Non-cardiac causes: Syncope is most commonly caused
by
conditions that do not directly involve the heart. These conditions
include:

Postural hypotension: Drop in blood pressure due to changing body
position to a more vertical position after lying or sitting;

Fainting after blood drawing or after certain situations
like urinating, defecating or coughing (situational syncope) due to a
reflex of the involuntary nervous system (called the vasovagal
reaction) that slows the heart and dilates blood vessels in the legs
in such cases people often feel nausea, sweating, or weakness just
before losing fainting.

Cardiac causes: Heart conditions that can cause
syncope or
fainting due to temporary loss of consciousness include:

To be sure, many of the causes of temporary loss of
consciousness can be detected by a careful history.
Dizziness after standing up in an older person suggests postural
hypotension. Temporary loss of consciousness after urinating,
defecating, or coughing
suggests situational syncope. Cardiac causes of temporary loss of
consciousness such as aortic stenosis or cardiomyopathy are
suggested by the occurrence of the event during exercise. Signs of
weakness localized to certain areas of the body with temporary loss
of consciousness suggest stroke.

The blood pressure and pulse are tested in the lying, sitting, and
standing positions. Unequal blood pressures in each arm is a sign
of aortic dissection. The heart is examined with a stethoscope to
listen for sounds that can indicate valve abnormalities. The nervous
system is tested for sensation, reflexes, and motor function to
detect conditions of the nerves and brain. An EKG is done to check
for abnormal heart rhythms. Other tests may include echocardiograms,
rhythm monitoring tests
(heart event recorders), and electrophysiologic testing for
abnormalities of the heart's electrical system.

When heart conditions
are not suspected, tilt-table testing can be used to detect causes of
temporary loss of consciousness. Tilt-table testing involves placing
the patient on a table with a foot-support. The table is tilted
upward and blood pressure and pulse is measured while symptoms are
recorded in various positions.

No treatment is needed for many non-cardiac causes of syncope
(such as postural hypotension, vasovagal reaction, and situational
syncope). The person regains consciousness by simply sitting or lying
down. The person is thereafter advised to avoid trigger situations,
to not strain while eliminating, to sit when coughing, to lie down
for blood drawing, etc.

Older people should have their medications reviewed and caution is
advised to slow the process of changing positions from lying to
standing. This simple technique can allow the body to adjust to the
new position (as the nerves to circulation of the legs adjust
slower in older person).